Is this right? 3 stage heater question? 0 & 1 do nothing..

[Hotshot]

Am I right? Or missing something...?

0 and 1 do nothing, but after looking at it opened up, it mechanically makes sense. What I don’t have is another 86 to compare it too.

What I can see after staring at this for a while is that maybe there’s a switch SUPPOSED to be where I’m drawing the numbers and it broke or was removed at some point.

Follow along, The only difference between zero and 1 is a click from the plastic detent ball. NO micro switches are engaged. That would explain why nothing kids on at 1...




Note smaller green gap, no engagement..



2 kicks on right switch.




3 engages the one on left..




The light works, just 2 fan can be noisy.

Do I need a new switch?

[Litle brother]

Originally Posted by Hotshot

Am I right? Or missing something...?

..







.?

Looks like there is space for a third micro switch in the location where you have written 1. Might control something that is not insalled in your car?


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[Hotshot]

Ya.. looking at the OEM switch where Pos 1 would go. Looking at the schematics I’m trying to figure out if it’s just a step, for gores somewhere else

[Snitzler]

Pulled from my 1988 3.2 coupe. If I remember correctly, 0 is off, 1 is the standby position which did nothing and 2 and 3 boost the fan speed.
I removed the useless switch from the center console and the blowers work fine. I mounted a pen and pencil holder onto the center center console to hold my coffee. Works great.

[aj88cab]

Do you have foot-well blower fans? For cars with the foot-well blowers speeds 0 & 1 are the same (slow) speed. The reason is to keep air moving thru the foot-well blowers anytime the heat leavers are on (pulled up), otherwise the foot-well fans can overheat and cause issues with the plastic fan housings.

I am pretty sure there is not a missing switch in your controller. It looks the same as mine did when I had it open. Same as yours & Snitzler's images above.

I am not 100% sure if this is the case in cars without the foot-well blowers.

[Hotshot]

Very cool info guys. Thx so much for posting a pic of the switch. I do have working foot blowers and that makes sense. The new replacement switch shows another switch and a mess of wires all going to the same connector.

This may be an “ it works leave it alone thing”. 2 and 3 blast pretty good.

Thx again, Pics are key for comparison. And thus learning.

[aj88cab]

If you have working foot-well blowers you are ahead of the game
Just make sure they are running on the 0 & 1 setting to keep air flowing.

[Hotshot]

I pull the levers, I get the rear fan on and heat. I can’t tell but I don’t think I get the well fans. 2-3 ohhh ya

[aj88cab]

The FW blowers can be pretty quiet on the 0 & 1 setting. You might have to put your head down close to hear. If setting 2 is working, most likely 0 & 1 are as well.

[Hotshot]

Originally Posted by aj88cab

The FW blowers can be pretty quiet on the 0 & 1 setting. You might have to put your head down close to hear. If setting 2 is working, most likely 0 & 1 are as well.

So, I checked.

When I pull the leaver on 0-1 the right fan come on. Super quiet.

2-3 both right and left comes on. Lefts starting to squeal and the right is tip top..

[aj88cab]

Take the left FW Blower out of the car, open the housing and you will probably find the fan cage has been rubbing on the plastic housing, either above or below the fan cage. It may look melted and have burrs. Sand the housing smooth, put a few drops of oil on the bearings (sleeve bearings).

This thread will help.
Footwell blowers squeaky, how to fix.


If the bearings are worn and have a lot of lateral play, its done...get out your wallet.

Some folks have had luck slightly moving the fan cage on the shaft as shown in the above thread so it doesn't contact the housing, but it is tight with age and can damage the cage if you are not careful (ask me how I know). Don't force it, if it doesn't look like it wants to move, leave it.

Put it back together and if you are lucky you might get a another year or two from it. But unfortunately, these are generally temporary fixes.

[monkeyodeath]

Just had my heater fan switch out a couple weeks ago to diagnose a problem. I saw the same setup -- 0 and 1 are the same thing, no microswitches engaged. It's like a dummy switch.

As long as the fans run slowly when you pull the levers at 0 and 1, you should be good.

The duplicate fan settings are baffling, though. Did someone make a mistake in ordering switches? Did they order bulk 4-position switches for something else and figure they'd throw them in the 911 instead of using a new part? Did they think that the discerning 1980s sports car buyer would never get a vehicle with only 3 fan settings?

[aj88cab]

Originally Posted by monkeyodeath

The duplicate fan settings are baffling, though. Did someone make a mistake in ordering switches? Did they order bulk 4-position switches for something else and figure they'd throw them in the 911 instead of using a new part? Did they think that the discerning 1980s sports car buyer would never get a vehicle with only 3 fan settings?

The original heat systems did not have engine blowers or foot-well blowers. Originally it was just the engine cooling fan providing the air flow. Later the engine blower was added to help move the heated air at slower engine speeds. Finally the Foot-well blowers were added. With the FW blowers in the path it was necessary to have the FW blowers running any time the red heat levers were ON (up) for two reasons. If the FW blowers were actually OFF with the levers up, they would be blocking the air flow. Secondly, the heated air from the heat-exchangers is pretty hot, and the plastic housing & fan cage could be damaged if they were not moving the air though FW blowers. Porsche's solution for the FW Blowers appears to have been to have the 0 & 1 settings the same slow speed...typical quirky air cooled Porsche approach

As to whether they originally intended the "0" setting to be OFF, and discovered the issues after the fact, is an answer that will probably be forever lost in history!

[Hotshot]

You guys rock. Thx again. Ya the left one only squeals now n then lower. High seems fine. Pretty soon I will have all the electrics working stalk. The good news is the PO put in a new rear fan as I have the old cage and burned out motor.

Having the schematics helps too.

[Hotshot]

Took out the blower, nothing seems rubbing. Indeed it was working on. 0-1. I couldn’t get the fan off the motor and didn’t want to break it. Used a thin electric motor oil the model train guys use on small electric motors.

Still I got on shrill when going 3-2.

Must be he bearings in the motor.

What the best place to replace them?

[T77911S]

position 1 probably just uses the air from the engine fan to blow heat.

I think the autoheat does the same thing. would have to look again.

[Hotshot]

Originally Posted by T77911S

position 1 probably just uses the air from the engine fan to blow heat.

I think the autoheat does the same thing. would have to look again.

No it’s wired to go on. And it makes sense. With the addition of the blowers, as soon as you pull the lever up, the motors go. Yes very lightly, but the need to spin for airflow because if my, they block it.

It seems a lot are done this way vs the three switch method.

[monkeyodeath]

Originally Posted by Hotshot

Took out the blower, nothing seems rubbing. Indeed it was working on. 0-1. I couldn’t get the fan off the motor and didn’t want to break it. Used a thin electric motor oil the model train guys use on small electric motors.

Still I got on shrill when going 3-2.

Must be he bearings in the motor.

What the best place to replace them?

If you can get the bearings out enough to read the numbers on the side, pretty easy to just google the number to find places that sell it.

Barring that you can take some measurements. I think McMaster sells a pretty diverse array of bearings.

[Hotshot]

That’s a very good idea. I’ll wait for that until it’s really bad. I wonder if tots the same as my old Bosh blower motor with a fried brush. Wouldn’t that be awesome.

[Driven97]

I'm pretty amazed the aftermarket has yet to come up with an alternative to the $500/ea footwell blowers.